This invention relates to a method of winning copper accompanying metals from sulfidic ores, post-flotation deposits, and waste products in the pyrometallurgical processing of copper ores.
Conventional methods of winning copper and accompanying metals from sulfidic ores and post-flotation deposits consist in leaching materials containing insoluble metal compounds, followed by further treatment to obtain desired metals, usually by electrodeposition, cementation, or reduction by means of hydrogen gas.
The known leaching liquors include acidic substances such as sulphuric, nitric or hydrofluoric acids, salts of strong acids, alkaline substances such as hydroxides, or carbonates, complex forming agents among which used are cyanides, ammonia (Polish Pat. No. 51794), as well as numerous organic complexing agents, usually in aqueous solution, such as versenic acid (Polish Pat. No. 79872), aliphatic amines, carboxylic acids, and nitriles.
A frequent disadvantage of the above methods is the necessity of a preliminary treatment of the ore, or of conducting of the leaching process, at elevated temperatures, resulting in increased energy expenditure. Irreversible reactions of some leaching agents result in their increased consumption. In adition, the variety of minerals in the ore offers difficulties in a proper selection of the leaching agent, ensuring high degree of recovery of the metal. Most of the leaching liquors used are highly corrosive, resulting in serious difficulties in construction and technology. Acidic leaching is accompanied by toxic gas emission, in particular of sulphur dioxine, and nitrogen oxides, producing technological complications resulting from the necessity of utilization of these gases. In addition, an increased consumption of the leaching agent in accompanying reactions results in the latter case. For example, most of the acid used in leaching rocky materials containing calcium and magnesium carbonates is consumed in decomposition of the barren rock. Similar losses occur in metal winning from the silicates containing ores using alkaline leaching liquors able to dissolve silica. The cyanide methods frquently used in hydrometallurgy, particularly in leaching copper compounds, creates serious biological threats, necessitating complicated technologies using closed systems.